Snowboards are constituted by a single board on which shoe bindings must be associated; these bindings usually must allow the skier to achieve a position which is slightly rotated with respect to the longitudinal axis of the board.
The technology used so far to provide ski bindings is not applied directly to the case of snowboards: in this regard, patent DT 23 56 052 discloses a safety ski binding with a plate which can be accommodated on the ski; the shoe is engaged with the tip by means of supporting elements which are fixed on the plate and with the rear part by lateral supporting elements which are fixed to the plate.
This conventional solution entails drawbacks, since it cannot be transferred directly to an application on snowboards, since the user must arrange the shoes at an angle with respect to the longitudinal axis of the board and so as to be able to preset slight rotations of the shoes in order to improve control of the board.
In snowboarding it is also necessary to have perfect adhesion of the shoe or of most of it to the board, since steering is achieved by shifting the weight of the body from one side to the other of the board; in ski bindings of the illustrated kind, instead, layers of snow or ice can form between the skis and the sole of the shoe, consequently worsening the control of the board.
In relation to the specific use of snowboards, French patent no. 2,669,237 discloses an adjustable safety binding for skiing boards, also known as snowboards, which comprises a base which is meant to be fitted to the board and a top part which is connected to detachable shoe locking means; the base comprises a spherical pivot which is complementary to a spherical pivot of the top part, so as to provide a ball-and-socket joint which allows mutual angular adjustment of the base and the top part with three degrees of angular freedom and furthermore provides a means for locking the base and the top part.
In this solution, therefore, an angular adjustment of the position of the shoe with respect to the board is substantially achieved, but the connection and disconnection of the shoe with respect to the binding is not easy, since it is in any case locked by the interaction of means which act on the tip and on the heel unit of the shoe; all this entails difficult transmission of forces from the foot to the board, since these forces must be located in the small area of interaction between the base and the top part, dissipating for example the forces applied during body weight shifting and possibly deforming the components which are mutually rotatably associated.
The use of any flexible elements does not solve the problem, since it leads to an unwanted dissipation of forces and therefore the skier is unable to have good sensitivity on the board, since he cannot directly transmit the forces applied to the shoe.
U.S. Pat. No. 5,299,823 relates to a snowboard binding which comprises a fixed jaw for coupling one side of a shoe and a movable jaw which is fitted so as to engage the opposite side of the shoe.
A lever places the seat for the movable jaw in a locked condition, in which the fitted movable jaw is fixed so as to be in a locked condition with the shoe; in an intermediate condition, in which the seat for the movable jaw can be shifted laterally towards a free condition; and in a released condition, in which the seat for the movable jaw can be either moved safely towards the free condition or can be promptly moved towards the free condition in contrast with a spring.
This solution is structurally complicated and is subject to possible jamming of its components, which are affected by several relative movements in order to lock and/or release the shoe.
All these solutions furthermore have the drawback that they require to place the board on a level surface in order to achieve easier fixing of the shoe, but this is a seldom available condition.